Dual evaporator refrigeration system



United States Patent O 3 537,274 DUAL EVAPORATOR REFRIGERATION SYSTEM Ralph B. Tilney, St. Louis, Mo., assignor to Alco Controls Corporation, Creve Coeur, Mo., a corporation of Missouri Filed Oct. 18, 1968, Ser. No. 768,651 Int. Cl. F25b 13/00 US. Cl. 62-324 9 Claims ABSTRACT OF THE DISCLOSURE A dual evaporator refrigeration system piped to permit alternate connection of the evaporators for cooling while using the liquid refrigerant as the source of heat for defrosting the disconnected evaporator.

BRIEF DESCRIPTION OF THE INVENTION This system has the usual components, which include a compressor, a condenser, a receiver and an expansion device. However, there are two separate evaporators, and there is a fourway valve for alternately connecting one or the other evaporator to the outlet side of the expansion device. Because of the piping, the other evaporator is connected in the liquid refrigerant flow line so that liquid refrigerant passes through it. This liquid refrigerant serves as the source of heat for defrosting the evaporator not being used. Each time the four-way valve is actuated, the two evaporators are interchanged so that the defrosted evaporator then acts as the evaporator for the refrigeration system and the other evaporator is defrosted by the circulating liquid.

A modification accomplishes the same results without the requirement of a two-way expansion valve. In the modification, a separate expansion valve is used for each evaporator.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of the dual evaporator refrigeration system.

FIG. 2 is a schematic diagram of a modification of the refrigeration system.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the dual evaporator refrigeration system 10 has a compressor 11 having its discharge side connected by a pipe 12 to a condenser 13. The outlet side from the condenser 13 is connected by a pipe 14 to a receiver 15. Another pipe 16 leads from the receiver to a conventional four-way valve 17. A pipe 18 leads from the four-way valve 17 to the suction side of the compressor 11.

There are two evaporators, 19 and 20. One evaporator 19 is connected by a pipe 21 from one port of the fourway valve 17 and the other evaporator is connected by a pipe 22 from another port of the four-way valve 17. The evaporator 19 has a pipe 23 connecting its outlet to one side of an expansion valve 24. Another pipe 25 connects the outlet from the evaporator 20 to the other side of the expansion valve 24. There is the usual tube 26 leading from the valve 24 to a sensing bulb 27. The sensing bulb 27 is positioned adjacent the suction pipe 18 leading to the compressor 11.

The four-way valve 17 may be any conventional fourway valve that alternately connects the pipe 16 to one of the pipes 21 or 22 and the pipe 18 to the other of the pipes 21 or 22 not connected to the pipe 16. When the valve 17 is actuated, these connections are reversed. Actuation of the valve 17 may be manually or it may be set on a timer to be reversed at predetermined time intervals. By this alternate switching of the valve 17,

3,537,274 Patented Nov. 3, 1970 only one of the evaporators 19 or 20 is downstream of the expansion device 24 to perform its evaporating function. Since the other evaporator is upstream of the expansion valve 24, it is subjected to the circulation of hot liquid flowing from the condenser 13. This hot circulating liquid serves as a heat source for defrosting the non-functioning evaporator.

Assuming for example that the valve 17 is set to connect the pipe 16 to the pipe 21 and the pipe 18 to the pipe 22, refrigerant is drawn through the pipe 18 to the compressor 11 where its pressure is increased. The refrigerant gas flows from the compressor to the condenser 13 where the refrigerant is converted to liquid and thereafter discharged to the receiver 15. The hot liquid flows through the pipe 16 to the valve 17 and from the valve 17 through the pipe 21 to the evaporator 19. Since this refrigerant is still in the hot liquid condition, it flows through the evaporator 19 and acts as a defroster to defrost the evaporator 19. The liquid refrigerant then flows through the pipe 23 to the expansion valve 24 where it is expanded to a lower pressure under the control of the remote bulb 27. The low pressure refrigerant flows through the pipe 25 and is evaporated in the evaporator 20 as the evaporator 20 performs its cooling functions. The evaporated refrigerant gas from the evaporator 20 flows through the pipe 22 and the four-way valve 17 back to the pipe 18 for repeating the cycle.

When the four-way valve 17 is reversed, the same process takes place, except that the pipe 16 is now connected to the pipe 22 and the pipe 18 is now connected to the pipe 21. Therefore, the liquid refrigerant from the receiver 15 flows from the pipe 16 through the four-way valve 17 to the pipe 22 to defrost the evaporator 20. Since the evaporator 19 is now downstream of the expansion device 24, it is subjected to the flow of low pressure expanded refrigerant and now functions as a normal evaporator, returning the evaporated refrigerant by way of the pipe 21 and the four-way valve 17 to the compressor suction pipe 18.

FIG. 2 shows a modified refrigeration system 30. This modified system 30 has the same components as the system 10. Thus, in the refrigeration system 30, the compressor 11 is connected by a pipe 12 to the condenser 13, the outlet from which is connected by a pipe 14 to the receiver 15. The outlet from the receiver 15 is connected by a pipe 16 torthe four-way valve 17 and the pipe 18 leads from the four-way valve 17 to the compressor 11. This system also incorporates the two evaporators 19 and 20 with the evaporator 19 being connected by a pipe 21 to the four-way valve 17 and the evaporator 20 being connected by a pipe 22 to the four way valve 17.

In the refrigeration system 30, there are two expansion valves 31 and 32. The inlet to the expansion valve 31 is conected by a pipe 33 leading from the evaporator 20. The outlet from the expansion valve 31 is connected by a pipe 34 to the evaporator 19. The inlet to the expansion valve 32 is connected by a pipe 35 from the evaporator 19. The outlet from the expansion valve 32 is connected by a pipe 36 to the evaporator 20. The pipes 34 and 35 are joined together between the expansion valve 31 and the evaporator 19, as shown, and the pipes 33 and 36 are joined together between the expansion valve 32 and the evaporator 20.

Unless the expansion valves 31 and 32 are of the kind having maximum operating pressures or are other kinds that block reverse flow of refrigerant through them, there should be check valves (not shown) in the pipes 34 and 36 between the expansion valves 31 and 32 and the junctions between the pipes 34 and 36 and the pipes 35 and 33 respectively.

The system 30 of FIG. 2 operates in the same manner as has been'described in connection with the'system except that when the four-way valve 17 is actuated, alternate ones of the expansion valves 31 and 32 are operative. Thus, in one condition, refrigerant flows from the pipe 16 through the four-way valve 17 to the pipe 21, the evaporator 19, the pipe 35, and the expansion device 32 where it is expanded and then flows through the pipe 36, the evaporator 20 and the pipe 22. In the other condition, the refrigerant flows from the pipe 16 through the four-way valve 17, throughthe pipe 22, through the evaporator 20, the pipe 33, the expansion valve 31, the evaporator 19, and the pipe 35. V

Variouschanges and modifications may be made within this invention as will be readily apparent to those skilled in the art. Such changes and'modifications are within the scope and teaching of this invention ,as de'- fined by the claims appended hereto.

What is claimed, is:

1. A refrigeration system comprising a compressor having a suction inlet and a discharge outlet, a condenser connected to the discharge outlet, expansion means for reducing the pressure of refrigerant flowing from the condenser, a pair of evaporators connected in series and valve means for alternately connecting one evaporator between the upstream side of the expansion means and the downstream side of the condenser and the other evaporator between. the suction side of the compressor and the downstream side of the expansion means whereby at any given time liquid from the condenser is circulating through the one evaporator, and cold vapor from the expansion means is .circulating through .the other evaporator.

2. The refrigeration system of claim 1 wherein the valve means comprises a four-way valve to alternate the aforesaid connections to the evaporators.

3. The refrigeration system of claim 1 wherein the expansion means comprises a single two-way expansion device connected between the evaporators.

4. The refrigeration system of claim 1 wherein the expansion means comprises two expansion valves each connected to the upstream side of an evaporator, and refrigerant conduit means for by-passing the expansion .valve on the upstream side of the said one evaporator.

V 4 5. The refrigeration system of claim 4 wherein thee p'ansion valves have maximum operating pressures.

6'. A refrigeration system comprising a compressor, a condenser, expansion means and first and second evaporators, piped in series, refrigerant conduit means, and valve means in the conduit means'forconnecting the first evaporator in the path of refrigerant downstream of the condenser and upstream of the expansion means and connecting the second evaporator in the path of refrigerant downstream of the expansion means and upstream of the compressor and alternately for reversing. the connections of the first and second evaporators.

7. The refrigeration system of claim 6 wherein the expansion means comprises .a separate, expansion device upstream of each evaporator. I V

8. A refrigeration system comprising a compressor having a suctioninlet and'a discharge outlet, a condenser connectedto the discharge outlet, evaporators, expansion valve means connected in series between the evaporators, the evaporators and expansion valvermeans combination being connected in series between the condenser outlet andcompressor inlet; and valve means for alternately changing the direction of flow of the refrigerant from the condenser through the'evaporator and expansion valve means combination. i

9. The refrigeration system of claim 8 wherein the expansion means comprises two directional expansion valves connected betweenthe evaporators such that one expansion valve will allow refrigerant to, flow in one direction through the series combination and the other expansion valve allows refrigerant to fiow in the other direction through the series combination.

References Cited UNITED STATES PATENTS 2,496,143 1/ 1950 Backstrom 62278 2,960,840 11/1960 Hosken ,62 8l 2,978,877 4/1961 Long 62278 WILLIAM J. WYE, Primary Examiner US. Cl. X.R. 

